Stabilization of organic compounds



Patented Mar. 31, 1953 STABILIZATION OF ORGANIC COMPOUNDS Ralph E. Thompson, Hinsdale, 111., assignor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware No Drawing. Application September 16, 1950, Serial No. 185,336

14 Claims. 1

This application is a continuation-in-part of my copending application Serial No. 5,209, filed January 29, 1948, now abandoned, and relates to the stabilization of organic compounds which tend to deteriorate in storage or in use due to oxidation reactions.

Various organic compounds are unstable in storage or during treatment and form undesirable gums, undergo discoloration, form sludges or otherwise deteriorate due to oxidation, polymerization or other undesired reactions. Included among the organic compounds which undergo such deterioration are gasoline, diesel oil, mineral oil, lubricating oil, fuel oil, drying oil, greases, edible fats and oils, acetylenes and particularly vinyl acetylene, butadiene, isoprene, styrene and other vinyl aromatics, various unsaturated alcohols, acids, ketones, etc.

The invention is particularly applicable to the stabilization of unsaturated gasolines and still more particularly cracked and polymer gasolines. In storage or during treatment these unsaturated gasolines tend to form undesirable gums. The invention is also applicable to the treatment of aviation gasolines which tend to undergo deterioration due to the addition of tetraethyl lead fluid or due to other components in the gasoline.

The invention is also particularly applicable to the stabilization of edible fats and oils which generally are of animal or vegetable origin and which tend to become rancid, especially during long periods of storage prior to use. Typical representatives of these edible fats and oils include linseed oil, menhaden oil, cod liver oil, castor oil, olive oil, rapeseed oil, coconut oil, palm oil, corn oil, sesame oil, peanut oil, babassu oil, butter, fat, lard, beef tallow, etc. It is understood that other oils and fats may be treated within the scope of the present invention, including oils and fats which have previously been subjected to various treatments, such as blowing with air heat treatment, etc.

In another embodiment the present invention is particularly applicable to the treatment of crops by dusting or spraying in order to preserve food accessory factors such as carotene, vitamins, various fatty acids, alcohols, etc.

In one embodiment the present invention'relates to an organic material subject to oxidative deterioration containing an inhibitor prepared by reacting an aliphatic amine with a member of the group consisting of 1,4-dihydroxy-5,8-dihydronaphthalene and 1,4-dihydroxy-5,6,7,8-tetrahydronaphthalene.

In a specific embodiment the present invention relates to motor fuel normally tending to deteriorate in storage containing from about 0.001% to about 0.5% by weight of N-sec-butyl-N-methyl-lhydroxy-4-amino-5,6,7,8-tetrahydronaphthalene.

The novel inhibitors of the present invention may be represented by the following general structure:

N/R: R4 OH R4 R R1 R R I II R OH R N\ R R1 R /R1 5 a III IV R, R1, R2, R3, R4, and R5 may comprise hydrogen or alkyl radicals. When these groups comprise alkyl radicals, they preferably are selected so that the total number of carbon atoms in the inhibitor does not exceed about 25 Still more particularly, these compounds preferably comprise alkyl radicals containing from about 1 to about 4 carbon atoms and include such groups as methyl, ethyl, propyl and butyl.

General structure I above illustrates a l-hydroxy 4 amino-5,8-dihydronaphthalene. Pre ferred inhibitors of this class include those in which R. comprises an alkyl group and comprise such compounds as 1-hydroxy-4-methylamino- 5,8 dihydronaphthalene, 1 hydroxy 4 -ethylamino 5,8 dihydronaphthalene, 1 hydroxy- 4 propylamino 5,8 dihydronaphthalene, 1- hydroxy 4 butylamino 5,8 dihydronaphthalene, 1 hydroxy 4 dimethylamino 5,8 dihydronaphthalene, 1 hydroxy 4 diethylamino 5,8 dihydronaphthalene, 1 hydroxy- 4 dipropylamino 5,8 dihydronaphthalene, 1 hydroxy 4 dibutylamino 5,8 -dihydronaphthalene, N ethyl N methyl 1 hydroxy- 4 amino 5,8 dihydronaphthalene, N propyl- N methyl 1 hydroxy 4 amino 5,8 dihydronaphthalene, N butyl N methyl 1- hydroxy 4 amino 5,8 dihydronaphthalene, N propyl N ethyl 1 hydroxy 4 amino- 5,8 dihydronaphthalene, N butyl N ethyl- 1 hydroxy 4 amino 5,8 dihydronaphthalenaetc. ,1

Structure II illustrates a 1,4-diamino-5,8-dihydronaphthalene. Preferred inhibitors in this class include 1,4 diamino 5,8 dihydronaphthalene, 1,4 dimethylamino 5,8 dihydronaphthalene, 1,4 diethylainino 5,8 dihydronaphthalene, 1,4 dipropylamino 5,8 dihydronaphthalene, 1,4 dibutylamino 5,8 dihydro naphthalene, 1 methyl amino 4 ethylamino 5,8 dihydronaphthalene, 1 methylamino 4 propylamino 5,8 '--dihydronaphthalene, 1 methylamino 4 butylamino 5,8,- dihydronaphthalene, 1-ethylamino 4* propylamino 5,8 dihydronaphthalene, 1 ethylamino 4 1-- butylamino.-. 5,8 =dihydronaphthalene,- 1 propylamino: 4 -Ibuty1amino 5,8 dihydronaphthalene, etc; .thercase of the di (alkylamino) compounds it is .desirable that at least one of thealkyl groups is a-sec-alkyl group such as isopropyl orsec-butyla We 1 1 Structure III illustrates a l-hydroxy-4-amino- 5,6,7,8 tetrahydronaphthalene. Preferred inhibitors ofthis class include l-hydroxy-l-methylamino-5,6,7} e tetrahydronapthalene, 1 hydroxy-4 ethylamino-5,6,'7,8 tetrahydronaphthalene, 1-hydroxy-4-propylamino-5}6,7,8-tetrahydronaphthalene, .ij1-hydroxy-4-butylamino-5,6,- 7,8 tetrahydronaphthalene; 1'--- hydroxy4-dimethylamino-5,6;7,8-- tetrahydronaphthalene, 1- hydroxy-l-diethylamino 5,6,'7-,8 tetrahydronaphthalene, 1-hydroxy-4-dipropylamino-5,6,7,8 tetrahydronaphthalene, 1-hydroXy'-.4 dibutylamino-5,6,7,8-tetrahydronaphthalene, N- ether- N methyl-1-hydroxy-4-amino-5,6,7 ,8 tetrahydronaphthalene, N-propyl-N-methyl-l-hydroXy-, l -amino-5,6,'7-,8-tetrahydronaphthalene, N-butyl- N-methyl-l-hydroxy-4-amino-5,6,7,8etetrahydro naphthalene, N-propyl-N-ethyl -.1 hydroXy-4- amino-5,6,'7,8 --tetrahydronaphthalene, N-butyl- N-ethyl-l-hydroxy-'- 4,5,6,7,8w tetrahydronaphthalene, etc.

StructureIV illustrates a l,4-diamino-5,6,7,8- tetrahydronaphthalene. Preferred. inhibitors of this class include 1,4-1diamino-5,6;7,8-tetrahydronaphthalene, 1,4-dimethylamino 5,6,'7,8 tetrahydronaphthalene; "1,4 1- diethylamino 5,637,8- tetrahydronaphthalene, 1,4-dipropylamino-5;6,7- S-tetrahydrpnaphthalene,. 1,4'-'dibuty1amino- 5,6- 7,8 tetrahydron'aphthalene, 1 methylamino-4- ethylamino 5,6,7',8" tetrahydronaphthalene, '1- methylamino-4-propylamino-5;6;7;8 tetrahydronaphthalene; 1- methylamino-4-butylamino 5,6 7,8 +1 tetrahydronaphthalene; "1 ethylamino-4- propylamino 5,'6,7,'8 .-i-tetrahydronaphthalene, 1" ethylamino 4- 'butylamino= '5-,6,7,8-tetrahydronaphthalene, 1 -"propylamino I 4 L butylamino-5,637,8 tetrahydronaphthalene; etc.

It is understood that the 'compoundshereinbefore set forth comprise preferred"inhibitors and that compounds ofthese general structures otherwise substituted by suitable 'groups'are also included within 'the scope'qf; the present invention. For example,- other satisfactory and-in fact in many cases preferred inhibitors include those in which one or both 0;) ,tliehydrogenatoms attached to each nitrogen atoinare replaced by alkyl groups. Specificexam'ples of compounds of 'this class are specified in the list of preferred compounds of'th'e classillu'strated general Structures I and III. Similar di-substituted compounds of the diamino compounds illustrated by general Structures II and IV are comprised within the scope of the present invention. However, as hereinbefore set forth, it is preferred that the total number of carbon atoms in the inhibitors does not exceed about 25. r

- -Itis understood that'the inhibitors of the present invention may comprise the specific compounds named herein in admixture with various isomers thereof. For example, in the dihydrocompound the isom'ers may comprise corresponding compounds in which the double bond in the non-aromaticringhas shifted to a conjugated position and/or those in which the hydroxy and amino groupshave interchanged positions with respect to'an' a'lkyl group positioned on the nonaro'rnatic ring. In the tetrahydro compounds, the isomers will be of the latter type.

' Th'e'inhibitors of the present invention may be prepared in any suitable manner. In general, these'inhibitorsare prepared by the reaction of a 1,4 dihydroxy 5,ii-dihydronaphthalene or IA-dihydroXy- 5,-6;;7 -tetrahydronaphthalene with a suitablealiphatic amine'; "Suitable aliphatic amines include methyl amine; ethyl amine, propyl amine, isopropyl amine, -n-butyl amine, isobutyl amine, -sec-bu'tylamine, etc; {The reaction is generally effected b'yheat-ing the reactants at an elevated temperature andrecoverin'g'the products by extraction in suitable solvents; As a typical "example; a specific method'of preparationis hereinafterset-forth. In one m'ethod ofprparing lhydroxy-4-sec butylamino 5,8 dihydronaphthaleneand L4- di-sec-but'ylamino" -=5;a" dillydrohaphtlialene,

1 ,4-dihydr6Xy- 5,8 diliydronaph'thalne maybe heatedin-asealed tubewitHsec-butyl in'e-at an elevated temperature of about-2005C. When the diall'zylaminobb'inpdiind is ifis'iredth'e amount of secuty1amine and tne reaeuon time are in creased'in-- order 'to efit reaction of the amine Withbo'l'il'i'of the hydi 'ify groups;- After 't-he reaction has proceeded tb -th desired extent, the product-ma be" dissolvd in an organic solvent, such as ethe -pet rq1eumetner; and then extracted vvith a dilut'eadueoiis sodium hydroxide solution to remov th iinracted 'startihg material. Th''pibdut su sequent y extracted with Claisen solution to' reinoi th li-hydroxyA-secbutyl-5;8 dihydronapfithalne' and to thereby separate it ream 1,4 di sec -butylamino-5,S dihydronaph'thalene. The other alkylaznino substituted' compounds may be' 'pr'epared ina'simil'ar mannenby varying the starting reagents as desired; Similarly the tetrahydro-substituted compounds are made in substantially the same man-- her by "starting with 1,4 di-hydroxy-5,6,'Z,8-tetraliydronaphtha'lehel r F Whenit is desired to produce compounds contain'i'ng two*alkyl-groups"attached" to-the' same pound may be treatedwith a suitablealkylation agent such" as dim'ethyl 'suliata' diethyl 1 sulfate, propyl chloride, etci in order'toproduce the dethe inhibitor may be used in conjunction with a synergist, such as phosphoric acid, ascorbic acid, citric acid, etc.

The following examples are introduced to further illustrate the novelty and utility of the present invention but not with the intention of unduly limiting the same.

EXAMPLE I The inhibitors used in the following runs were prepared in a manner similar to that heretofore set forth. These inhibitors were tested in a Pennsylvania cracked gasoline which had an induction period of 100 minutes. The inhibitor was added in a concentration of 0.01% by Weight to different samples of the gasoline and gave the results as shown in Table I.

lene l,4-di-sec-butylan1ino5,6,7,8-tetrahydronaphthalene... N-scc-butyl-N-methyl-l-hydroxy-4-amino-5,0,7,8-tetra- 1 hydronaph thalene It will be noted that inhibitors of the present invention increased the induction period from 100 minutes to at least 285 minutes and that the last mentioned compound, which comprised a tertiary amine, increased the induction period to 650 minutes. The inhibitor of the present invention therefore preferably contains a tertiary amine grouping.

EXAMPLE II The inhibitors used in the following run were prepared in a manner similar to that heretofore set forth. These inhibitors were added to lard which had a normal stability period of 9 hours as determined by the Swift test. This test is described in detail in the article by A. E. King, H. L. Roschen and W. H. Irwin, which appeared in the Oil and Soap, vol. X, No. 6, pages 105 to 109 (1933). In general, this test comprises bubbling air through a sample of the lard and reporting the number of hours until the lard develops a peroxide value of 20. 0.02% by weight of the inhibitors were added to this sample of the lard and gave the results as shown in Table II.

Table II Stability Inhibitor Period,

Hours 1-hydroxy-4-sec-butylamino-5,S-dihydronaphthalene 111 N-sec-butyl-N-methyl-l-hydroxy-4'amino-5,6,7,8-tetrahydrcnaphthalene 111 It will be noted that the inhibitors of the present invention increased the stability period of the lard from 9 hours to greater than 111 hours.

I claim as my invention:

1. An organic material normally subject to oxidative deterioration containing, as an inhibitor for said deterioration, a small amount of. an inhibiting compound selected from the group consisting of a l-hydroxy-4-amino-5,8-dihydronaphthalene, a 1,4-diamino-5,8-dihydronaphthalene, a 1-hydroxy-4-amino-5,6,7,8-tetrahydronaphthalene, and a 1,4 diamino 5,6,'7,3 tetrahydronaphthalene.

2. Unsaturated gasoline normally tending to deteriorate in storage containing, as an inhibitor for said deterioration, a small amount of a 1-hydroxy-4-amino-5,8-dihydronaphthalene.

3. Unsaturated gasoline normally tending to deteriorate in storage containing, as an inhibitor for said deterioration, a small amount of a l-hydroxy-4-amino-5,6,'7,B-tetrahydronaphthalene.

4. Unsaturated gasoline containing a small amount of a l-hydroxyi-alkylamino-5,8-dihydronaphthalene.

5. Unsaturated gasoline containing a small amount of a l-hydroxy-4-alkylamino-5,6,7,8- tetrahydronaphthalene.

6. Cracked gasoline containing from about 0.001% to about 0.5% by weight or N-sec-butyl N methyl 1 hydroxy 4 amino 5,8 dihydronaphthalene.

'7. Cracked gasoline containing from about 0.001% to about 0.5% by weight of N-sec-butyl- N methyl 1 hydroxy 4 amino 5,6,'7,8 tetrahydronaphthalene.

8. Edible fats and oils normally tending to deteriorate in storage containing, as an inhibitor for said deterioration, a small amount of a l-hydroxy-4-amino-5,8-dihydronaphthalene.

9. Edible fats and oils normally tending to deteriorate in storage containing, as an inhibitor for said deterioration, a small amount of al-hydroxy-4-amino5,6,7,S-tetrahydronaphthalene.

10. Lard containing from about 0.001% to about 0.5% by Weight of N-sec-butyl-N-methyl- 1-hydroxy-4-amino-5,8-dihydronaphthalene.

11. Lard containing from about 0.001% to about 0.5% by weight of N-sec-butyl-N-methyl- 1 hydroxy 4 amino 5,6,7,8 tetrahydronaphthalene.

12. A composition as defined in claim 1 further characterized in that said organic material comprises unsaturated gasoline.

13. A composition as defined in claim 1 further characterized in that said organic material comprises a fatty substance.

14. A composition as defined in claim 1 further characterized in that said organic material comprises lard.

RALPH B. THOMPSON.

REFERENCES CITED UNITED STATES PATENTS Name Date Missbach Sept. 28, 1937 Number 

1. AN ORGANIC MATERIAL NORMALLY SUBJECT TO OXIDATIVE DETERIORATION CONTAINING, AS AN INHIBITOR FOR SAID DETERIORATION, A SMALL AMOUNT OF AN INHIBITING COMPOUND SELECTED FROM THE GROUP CONSISTING OF A 1-HYDROXY-4-AMINO-5,8-DIHYDRONAPHNAPHTHALENE, A 1,4-DIAMINO-5,8-DIHYDRONAPHTHALENE, A 1-HYDROXY-4-AMINO-5,6,7,8-TETRAHYDRONAPHTHALENE, AND A 1,4 - DIAMINO - 5,6,7,8 TETRAHYDRONAPHTHALENE. 